Electric cable



Jan. 19, 1943. l.. s. BURGETT 2,308,673

ELECTRIC CABLE Original Filed March 14, 1940 3 Sheets-Sheet l Jan. 19, 1943. L. s. BURGETT ELECTRIC CABLE Original Filed March 14'. 1940 3 Sheets-Shut 2 ff I l R wf mw 6 5f /3 M M/ /r Z a rm H m M m n w II IIA/1 Patented Jan. 19, 1943 ELECTRIC CABLE Lynn S. Burgett, Euclid, Ohio, assignor to The Clark Controller Company. Cleveland, Ohio, a

corporation of Ohio Original application March 14, 1940, Serial No.

323,971. Divided and this application September 12, 1940. Serial No. 356,463

4 Claims.

This invention relates to electric cables and terminals therefor, and particularly to cables for carrying currents of great amperage, and constructed to be flexible.

Cables of the class referred to are used for various purposes wherein the current to be conducted by the cable is o1 great amperage and wherein the cable must bend in use, one' illus` trative use being to conduct welding current to a moving welding gun or machine, in which case any lack of flexibility in the cable would interfere with the free movement of the gun by the operator thereof.'

The invention comprises various improvements over prior cables of this class, which appear in the following objects of the invention.

It is among the objects of the invention:

To provide generally an electric cable of relatively great amperage capacity having an improved quality of flexibility;

To provide generally an electric cable having improved means for conducting cooling uid, such as liquid, therethrough;

To provide in a cable of the multi-conductor class an improved construction of terminal for the ends oi the conductors by which electric connections made be made to the conductors of the cable; and/or by which cooling uid may be introduced into and circulated through the cable; and/or admitting of the practice of an improved method for securing the ends of the cable conductors to the terminals;

To provide generally an improved means for securing the ends of the conductors of a multiconductor cable to end terminals thereof;

To pnl .ride an improved means for an electric cable adapted to be constructed in various forms to adapt it to be attached to different types of apparatus;

To provide for multi-conductor cables of the liquid cooled type, improved means for insulating the conductors one from the other and for providing cooling liquid passageways through the cable;

To provide an improved construction of insulator for the conductors of a multi-conductor electric cable;

Other objects will be apparent to those skilled in the art to which my invention appertalns.

My invention is fully disclosed in the following description taken in connection with the accompanying drawings, in which:

Eg. 1 is a side elevational view of an electric cable embodying my invention, and illustrating one construction of terminal connector at the ends thereof;

Fig. 2 is a longitudinal sectional view of the right hand end of the cable of Fig. 1 and drawn to enlarged scale;

Fig. 3 is a sectional view taken from the plane 3-3 of Fig. 2 and with some of the parts thereof omitted for simplicity;

Fig. 4 is a view taken in the direction of the arrow l of Fig. 2;

Fig. 5 is a cross-sectional view taken from the plane 5 5 oi Fig. 2;

Figs. 6 and '7 are respectively plan and crosssectlonal views of an insulator which I may employ in the cable of Fig. 2, Fig. 7 being taken from the plane l-l of Fig. 6, and these views illustrating the sheet form in which the insulator is nrst made, the aforesaid Fig. 5 illustrating the insulator in its assembled condition in the cable;

Fig. 8 is a view in some respects diagrammatic for clearness, illustrating the overlapping of opposite edges of the insulator of Fig. 7 when it is assembled in the cable as in Fig. 5;

Fig. 9 is a view, a part of which is in elevation, a part of which is in longitudinal section, and a part of which has an outer portion broken away, illustrating the construction of an outer casing or hose of the cable of Fig. 2;

Fig. l0 is a view similar to a part of Fig. 9 illustrating a modification;

Fig. 11 is a cross-sectional view taken from the plane Il-II of Fig. 9;

Fig. l2 is a view similar to a part of Fig. 2 and illustrating certain steps of method which I may employ in securing conductors of the' cable to a terminal head thereof, the view being taken approximately on the plane i2-I2 of Fie'. 4:

Fig. 13 is a view in elevation illustrating a modied form of a terminal connector;

Fig. 14 is a view illustrating in longitudinal section another modification of one of the terminal connectors of Fig. 2 or of Fig. 13.

Referring to Fig. 1 of the drawings, I have shown at I the cable proper, and .at 2 2 end ter minals therefor. The terminals 2-2 may be alike or different, as will appear hereinafter, but as shown in the drawings, the terminals are alike and are generally of hollow walled form (see Fig. 2) and each comprises terminal heads Il and 28 insulated from each other by an insulator 33; and threaded openings IUE-|06 are provided in the opposite terminals 2 whereby coolant or cooling uid may be conducted into the cable at one end and out at the other. The terminal heads I'I-Il are connected to one set or group of conductors in the cable, and the terminal heads 23-28 are connected to another set or group of conductors, and connectors 2 and I are provided on the terminal heads I1 and 28 respectively, and as will be explained hereinafter, the connectors 3 and d may be constructed in various types to adapt them to be connected to various types of apparatus, such for exampleeas a transformer at one end of the cable and a welding gun at the other end, when the cable is to be used to carry welding current.

The right hand terminal 2 and the corresponding end of the cable are shown in longitudinal section in Fig. 2, and coordinate therewith, the terminal heads I1 and 28 being shown in Figs. 3 and 4 in elevation.

The main body of the cable as shown in Fles. 2 and 5, comprises a plurality of conductors in groups alternately arranged, as for example at 5 5-5 and 5 5-5 in Fig. 5-; and disposed around a longitudinal core of rubber or the like 1; and insulated from each other by a convoluted insulator B of rubber or like flexible insulating material, and surrounded by a tubular casing or hose 9.

The conductors 5 and 6 are preferably made up in a well known manner, of thread wires and strands woven or twisted into rope form to render thein flexible.

To simplify the drawing, particularly Fig. 2, the conductors 5 and 8 are illustrated as lying parallel to the axis of the cable; and in fact, may be disposed in this relationship, but I prefer to dispose the conductors in helical arrangement around the longitudinal axis.

In assembling the conductors 5 and 5, and the insulator 8, the conductors 5 5 may ilrst be laid around the core 1, and the insulator 8 laid thereon; and the conductors 5 5 then laid in convolutions in the insulator, to be presently described, and then the casing or hose 8 is telescoped longitudinally over the insulator and conductors, the

hose or casing being shorter than the insulator and conductors, so that the latter project out of the opposite ends thereof.

The insulator 8 is shown in Figs. 6 and 'l in the form in which it is rst made. Preferably it is made from rubber by an extrusion or other process into generally planar orl sheet form, comprising at or planar portions IIJ I8, and spaced loop portions or convolutions I I II between the planar portions, and in the present illustrative instance, where there are to be, three conductors 5 5-5, there will be three such convolutions. The outermost planar portion I8 at each side of the insulator, terminates in bent thinned edges I2 and I3. The sheet 8 may be made of considerable length, and at the time of making a cable of any chosen length, a piece from such long strip is cut oi to approximately the necessary length, to be referred to, and is then folded around the core 1 to cause it to take up the crosssectional shape shown in Fig. 5, wherein the loop portions II are disposed so that the conductors 5 5 may be laid therein and wherein the planar portions III-Ill bend so that they deilne a longitudinal cylinder firmly or tightly engaged with the inner wall of the hose 8 when telescoped thereover, as plainly shown in Fig. 5. The edges I2 and I8 of the strip, when bent into the form of Fig. 5, are disposed approximately as shown in Fig. 8.

Bending the sheet insulator from the form of Fig. 7 to the condition in Fig. 5, causes the convolutions I I, as shown for one of them in Fig. 5, to become divergent, and causes the side walls Il, Figs. 5 and 7, of each convolution to be disposed generally radially, as shown in Fig. 5.

It follows that when the core l, insulator l, conductors 5 5 and 5 6 and the outer sleeve or cover 9 are assembled as shown in Fig. 5, or Fig. 2, there are longitudinal passageways I5 Ii5 along the sides of the conductors 5 5 and longitudinal passageways I5 I5 along the sides of the conductors 5 5, the passageways I5 I5 being separated by thef insulator 8 from the passageways IG-IS, and the conductors 5 being insulated from the conductors 5. t Ii the conductors 5 5 and 5 8 are to be disposed in helical arrangement around the core. the sheet 8 is folded around the core 'I so that its edge portions overlap on a helical zone thereby disposing the convolutions II in helical arrangement.

The assembled cable proper, made "as above described, is now joined to the hollow walled terminals 2 2 as follows, and as shown for one of them in Fig. 2.

The connector 3 is joined to a terminal head II, preferably by being made integral therewith as a casting of copper or other highly electrically conducting material, and a material to which solder or other fusibleV metal will adhere,\ y

for a purpose to be described. The terminal head Il comprises a central cylindrical opening I8, the periphery of which is outwardly radially recessed by a plurality, such as three, circular recesses I8 I8, and inwardly toward the cable proper and beyond the recesses, the terminal head I1 has an annular shoulder 28, into which is tted and secured, for example by soldering, a short tubular sleeve 2 I slightly larger in outside diameter than the inside diameter of the outer hose or casing, and larger on its inside diameter than the diameter of the assembled conductors and insulator. The terminal head I'I is also rprovided with a plurality of threaded holes 22.

For the next |step of the assembling operation. the conductors 5 and 5 and the insulator 8 are telescoped or projected through the sleeve 2I and opening I8 of the terminal head I1, and the hose 9 is concurrently telescoped over the sleeve 2l, which stretches it tight thereon, to seal it liquid tight therewith, and it is further sealed and secured thereon against displacement by a wrapping of wire shown at 23, Figs. l and 2. The outer conductors 5 5 are now bent outwardly radially, as shown at 24, Fig. 2, and laid in the recesses I9, and an assembling sleeve 25 is telescoped into the opening I8 substantially iltting the same and forcing the ends of the conductors into the recesses I9, the wall of the recesses and adjacent parts of the sleeve 25 constituting pockets into which the ends of the conductors are firmly lodged. I'he three conductors 5 are disposed in this manner and their end portions which extend beyond the terminal head I1 are then cut oil as at 26 prefer ush with a transverse plane 21 on the ter nal head I1. Solder or other fusible metal is then applied by well known heating means to the ends of the conductors 5, at 26 in the recesses I8, to securely Join the wires thereof together, and to integrally unite them with the terminal head II at the walls of the recesses I8.

The other terminal head 2B, Figs. 2 and 4. has a transverse planar face 28, and a generally cup form interior 30, and an inwardly open pocket 3|. The ends of the conductors B are now cut on as at 32, Fig. 2, to a measured length beyond the plane 21 referred to, and the face 29 of the terminal head 23 is placed upon the face 21 of the terminal head I1 with an insulating washer 33 therebetween, and bolts 34-34 are projected through insulating sleeves 35 in the head 23 and through perforations in the insulator 33 and threaded into the threaded holes 22 to rigidly seal and clamp the terminal head 28 upon the terminal head Il with the ends of the conductors 6 in the pocket 3|.

The terminal head 28 has a plurality, such as two, pipe threaded openings |06 and I 06A, extending therethrough and communicating with the cup form interior 30.

'I'he threaded openings |06 and IGEA may be variously disposed. As show'n in Fig'. 4, in the form illustrated, they are disposed at an angle of approximately 120 degrees with each other but may, as will be understood, be disposed dlf ametrically opposite, or otherwise.

Before the terminal head 2'8 is bolted on, as described, the insulator 8 is cut off at a point within the cup form interior 30, for example, as shown at 36, short of the pocket 3| For the next step of the assembling operation, the cable, illustrated thus far in horizontal position, is supported vertically, as indicated in Fig. l2, which disposes the pocket 3| at the lowermost point of the terminal head 28. By means of a blow torch or other heat supplying means 31, the terminal head 28, and particularly the pocket, 3| thereof, are heated, thus heating the end portions of the conductors 6 5; and a wire or stick 38 of solder or other fusible metal is projected through one of the said pipe threaded openings, for example the opening IDB, and into engagement with the hot head 2B and conductors 6, and the solder melts and flows around the conductors filling the pocket 3| and up to a level such as that shown at 39 joining the conductors to each other and to the wall of the pocket. This operation may be viewed through the other opening IUGA, and the filling with solder may therefore be stopped at a suitable observed level 39.

Upon removing the source of heat, and the soldering stick 38, the solder sets and integrally joins the conductors 6 to the terminal head 28.

The opposite end of the cable is assembled in the same way as that just described. The electric circuit through the cable will be seen to be from one of the connectors, say the connector 4. from a current source, through the inner conductors E, out at the other connector 4, to apparatus to be energized and back therefrom through the connector 3, and through the outer conductors 5, to the other connector 3, and to the source, as an illustrative use.

Cooling liquid may be circulated through the cable. By one method, one of the openings, say IDEA, is closed by a plug 40, Fig. 4, and a cooling liquid conduit has a threaded terminal thereof threaded into the other opening |06. Cooling liquid therefore will enter the cup form interior 30 and there divide, part flowing around the conductors 8 6 and longitudinally through the passages l6--I5, and out through a corresponding chamber and conduit at the other end of the cable; and part flowing from the cup form interior 30 through the opening I8, and longitudinally through the passageways |5|5 and out at the other end of the cable; thus flowing in two streams, each stream in direct contact with the metal of the conductors of one of the groups of conductors, and each stream insulated from the other by the insulator 8 through the maior part of the cable.

The assembling sleeve 25 may be left in the position of use, and as illustrated in Fig. 2, or after the conductors 5 have been soldered into the recesses I9, it may be removed.

'I'he connectors 3 and 4 are in the form of lugs with open ended slots to receive bolts for clamping them on to an apparatus part.

In Fig. 13 is illustrated a modification, in which the terminal heads I'IA and 28A and the insulating washer 33 and bolts 34 and sleeve 2| are similar to those in the form of Fig. 2, but the connectors thereof are different. 'I'he connector connected to the terminal head 2BA is in the form of a'longitudinally extending tongue 4I; having a perforation 42 therein by which it may be bolted to a point of use. The connector 43 connected to the terminal head IIA is provided with faces 44, 45, 4B and bolt holes 41 and 48 and a threaded bolt hole 53; laminated flexible conductors may be bolted to this connector by bolts projecting through the bolt hole 48 or into the threaded bolt hole 53 and the laminated conductors lying against one of the faces 44 to 46 in a well known manner or the connector 43 may be bolted to a point of use by a bolt through the hole 41.

In Fig. 14, is illustrated a modification of the outer terminal head 28B corresponding to the terminal head 28. 'Ihis terminal head has the cup form interior 30 and pocket 3| and holes 49 for the bolts, as in the form of Fig. 2. The electrical connector 5D projects axialhr from the terminal head and has threads 5| on the end thereof by which it may be screwed into an apparatus part, such as a welding gun, at the point of use, and has a cooling fluid duet 52 opening outwardly and therefore communicating with a corresponding duct in the part or gun to which the connector is threadedly Joined, and the duct 52 communicates with the cup form interior 30. With this form, as will be apparent, the cooling liquid which flows through the cable, may also flow through the part or gun to which the connector 50 is connected.

Referring now to Figs. 9, 10 and ll, which illustrate more particularly the construction of the outer hose or casing shown at 9, in Figs. 2 and 5. the hose is seen to comprise an outer layer or tube 53, and an inner tube'of rubber 54. with a. layer of cord 55 therebetween. In prior hoses, threads or small cords of woven arrangement have been disposed between inner and outer layers of rubber. In some cases, because of the woven character of the threads, the threads extend longitudinally of the hose or in helical direction therethrough, some following a right hand helix and others a left hand helix. In either case, and in all prior hoses of which I have knowledge, when the hose bends, at least some of the cords or threads of the fabric are put under tension, which resistsxthc bending of the hose and renders it stiif and of little ilexlbility, and causes the bent hose to buckle and assume an elliptical cross-sectional form.

In the hose of the present invention. the thread or cord 55 is solely helical, having no parts that are put under tension when the hose bends, and the base therefore has substantially the same flexibility as if it were made wholly of tion; and when used as the covering hose or casing of a cable such as that described above. increases enormously the iiexibility of the cable, over prior cables. For example, as an expert' ment I have found that a six-conductor cable, constructed and assembled complete as described hereinbeiore and as illustrated and of such a size that the loutside diameter of the assembled hose is 13/4 inches, can be wrapped freely spirally around a 6 inch diameter pipe without materially distorting the cross-sectional circular form. 'I'he helical cord 56 at the same time prevents distortion of the casing by cooling Iluld under pressure. Furthermore, the cable is rendered ilexible" in the torsional direction by the hose of this construction. A cable such as that illustrated and of 1% inches outside diameter and say 8 feet long. can be twisted merely by the force of the human hands to approximately 450 degrees from normal in the direction that winds up the helix of the conductors for the usual helical angle thereof and 720 degrees from normal in the other direction.

: In Fig. 9, I have illustrated the cord 55 as being a single cord, such as a cord of cotton, but it will be understood that the cord may be made of multiple parallel strands, or threads.

in the body and at the end o! the cable, the groups at the 'end oi the cable being connected respectively to two terminal heads of a generally hol- In making the hose of Fig. 9, a suitable process is to extrude the inner tube 5l and mount it on a mandril and then wind the cord 55 helically thereon, at such a pitch that there is a space 56 between adjacent convolutions. The space may be commensurable with the diameter of the cord. Then an extruded outer tube 53 is telescoped over the cords. 'I'hen the two tubes are vulcanized together, being thereby integrally united through the cord convolutions and on the portions 56 between adjacent convolutions.

In the modification Fig. 10, the cord 55A is wound at such a pitch that adjacent convolutions o! the cord touch or substantially touch each other and the outer and inner tubes 5I) and 54 are vulcanized together primarily through the fibers of the cord. l

A hose or casing made in this manner with its reinforcing thread or cord woundvhelically only while ail'ording great flexibility transversely whichis highly desirable as referred to, is elas tic and of. relatively little strength to resist stretching longitudinally, and this would render it inferior for some uses; but in the cable described above, such hose or casing is prevented from longitudinal stretching by being secured at its opposite ends as shown and described to the end terminals which in turn are secured to the longitudinally inelastic metal conductors 5 and 8 "1. In a flexible. heavy current cable. a Dlurlity of 'flexible conductors extending longitudinally of of the cable', and surrounded by a tubucasing. and disposed in two insulated groups low-walled terminal, one head being generally annular and connected to the casing. the other head being 'generally of cup form and secured at the end of the cup skirt to the annular head and insulated therefrom on transverse surfaces of the said skirt and said annular head respectively, a plurality of coolant passages extending through the body of the cable for conducting coolant over the two groups of conductors, and the passages all communicating with the cup interior of the cup form head, and an opening through the wall of the cup form head for supplying coolant to all of the passages.

2. In a ilcxible, heavy current cable, a plurality of exible conductors extending longitudinally of the body of the cable and surrounded by a tubular casing. and disposed in two insulated groups in the body and at the end of the cable, the groups atv the end of thecable being connected respectively to two terminal heads of a generally hollow-walled terminal, one head being generally annular and connected to the casing, the other head being generally of cup form andsecured at the end o1' the cup skirt to the annular head and insulated therefrom on transverse surfaces of the said skirt and said annular head respectively, a plurality oi coolant passages extending through the body of the cable for conducting coolant over of ilexible conductors extending longitudinally of' the body of the cable and surrounded by a tubular casing, and the conductors being substantially inelastic longitudinally and disposed in two insulated groups in the body and at the ends of the cable, the groups at the opposite ends of the cable being connected to corresponding terminals each comprising two terminal heads, one head being generally annular and connected to the casing, the other head being generally of cup form and secured at the end of the cup skirt to the annular head and insulated therefrom on transverse surfaces of the said skirt and said annular head respectively, a plurality of coolant passages extending through the body of the cable for conducting coolant over the two groups of conductors, and the passages all communicating at the opposite ends of the cable with the cup interiors of the corresponding cup form heads respectively, and an opening through the wall ot one cup form head for supplying coolant to all of the passages, and an opening through the wall of the other cup form headfor discharging the coolant, the tubular casing being composed of iiexible elastic material and having a cord incorporated in the material of the casing wall and disposed helically only about the casing axis to strengthen the casing wall radially without materially reducing its flexibility, the connection of the longitudinally inelastic conductors t'o the terminals preventinglongitudinal stretching of the casing,

4. In a exible, heavy current cable, a plurality of flexible conductors extending longitudinally of the body of the cable and surrounded by a tubular casing, and the conductors being substantially inelastic longitudinally and disposed in two insulated groups in the body and at the ends of the cable, the groups at the opposite ends of the cable being connected to corresponding hollow walled terminals each comprising two terminal heads, one head being generally annular and connected to the casing, the other head being generally oi cup i'orm and secured at the end of the cup skirt to the annular head and insulated therefrom on transverse surfaces of the said skirt and said annular head respectively. a plurality of coolant passages extending through the body of the cable for conducting coolant over the two groups of conductors. and the passages all communicating at the opposite ends of the cable with the interiors or the hollow walled terminals respectively. and means to conduct coolant from' a supply source into one hollow terminal and means to discharge the coolant from the other hollow terminal, the tubular easing being composed of iiexible elastic material and having a cord incorporated in the material of the casing wall and disposed helically only about the casing axis to strengthen the casing wall radially without matellnlly reducinz'lts exibility, the connection of the longitudinally inelastic conductors to the terminals preventing longitudinal stretching oi' the casing.

LYNN S. BURGEI'I. 

